An error correction technique influences a communication performance in wireless communications in which a communication signal essentially suffers some losses due to fading. As one type of error correction decoders for wireless communications, a soft-decision decoder, which has an input bit width of a plurality of bits so as to improve a reception performance, is known. The reception performance of the error correction decoder is improved when a bit width is increased, but that decoder has a tradeoff relationship, that is, an increase in bit width results in an increase in area, an increase in consumption power, and a decrease in maximum operation frequency. In order to relax this tradeoff relationship, an input signal of the soft-decision decoder is normalized in advance to a scale suited to decoding.
In a first example of normalization processing, a difference of maximum and minimum values or variance of amplitudes of reception subcarriers is used as a scaling criterion in an OFDM (Orthogonal Frequency Division Multiplex) receiver.
In a second example of the normalization processing, scaling is executed with reference to a mode value of log-likelihood ratios input to an error correction decoder.
The first and second examples of the normalization processing can obtain better results than a case without any scaling or a simple scaling method with reference to a power average of subcarriers. However, depending on multichannel fading situations, it is often difficult to perfectly apply the first and second examples of the normalization processing.